I've had a plethora of difficulties with my new iBook G4 since I bought it in February 05. Hard drive crapped out in August and had to be replaced - two weeks downtime - then in October the logic board died - four weeks downtime - and now I've got it back and the software is acting goofy. I'm sure it's just a matter of getting things updated, but all the back and forth between the rented computer and my "repaired" beast has made things cluttered.
With iPhoto I backed up the iPhoto Library and opened it again so I didn't get the you've-used-a-more-recent-version cop out, but it still crashes before it completes loading.
With iCal I get the same effect. I tried copying a more updated version (1.5.5) over from my rental, but the same thing happened, so I don't think it's the application file itself. I tried throwing out the Application Support > iCal folder and that didn't help.
With iTunes, also the same. Crashes before it begins.
Any idea if there's a patch to download or anything that makes it work?
I would install the iLife programs from your original install disk(s) and let Software Update update them to the latest version. Also, you might want to run a utility program like YASU (Yet Another System Utility) and let it do it's default cleanup of caches, etc.
HTH and please let us know what happens.